415.45. (a) A summons in an action for unlawful detainer of real
property may be served by posting if upon affidavit it appears to the
satisfaction of the court in which the action is pending that the
party to be served cannot with reasonable diligence be served in any
manner specified in this article other than publication and that:
(1) A cause of action exists against the party upon whom service
is to be made or he is a necessary or proper party to the action; or
(2) The party to be served has or claims an interest in real
property in this state that is subject to the jurisdiction of the
court or the relief demanded in the action consists wholly or in part
in excluding such party from any interest in such property.
(b) The court shall order the summons to be posted on the premises
in a manner most likely to give actual notice to the party to be
served and direct that a copy of the summons and of the complaint be
forthwith mailed by certified mail to such party at his last known
address.
(c) Service of summons in this manner is deemed complete on the
10th day after posting and mailing.
(d) Notwithstanding an order for posting of the summons, a summons
may be served in any other manner authorized by this article, except
publication, in which event such service shall supersede any posted
summons.